Inbox rotation spreads your sending across several mailboxes so no single account exceeds a safe daily volume.
How to use it
There's no separate setting to enable. Rotation happens automatically whenever a campaign has more than one sending account.
Open your campaign's settings.
In Select Account, choose two or more mailboxes.
Save.
Sending is then distributed across those accounts automatically, in rotation.
Why it matters
Every mailbox has a safe daily ceiling. If you need to send 300 emails a day, doing it from one mailbox will damage its reputation and land you in spam. Spreading it across six mailboxes at 50 a day each keeps every account in a safe range.
Rotation also limits your risk: if one mailbox develops a deliverability problem, the rest of your campaign keeps running.
What happens when the daily limit is reached
Each mailbox has a daily sending limit. When all of a campaign's sending accounts have hit their daily limit but leads still remain, the campaign doesn't stop — it automatically reschedules the remaining emails to the next working day, respecting your campaign schedule (working days and hours).
You'll get a notification confirming this — "Campaign Rescheduled – Daily Limits Reached" — telling you when sending will resume. Sending then picks up on the next working day and continues until the campaign finishes.
This is the main reason to send from more than one mailbox: the more accounts in your rotation, the more emails you can send per day before hitting the ceiling, and the fewer days your campaign takes to complete.
An email account can only run one campaign at a time
An email account that's already assigned to a running or scheduled campaign won't appear in the account list when you set up another campaign. This prevents the same mailbox from being overloaded by two campaigns sending at once, which would blow past its daily limit and hurt deliverability.
If a mailbox you expect to see is missing from the Select Account list, it's almost certainly already in use by another active campaign. It becomes available again once that campaign completes or is paused, or you can free it up by removing it from the other campaign.
Best practices
Warm up every mailbox in the rotation, not just the first one. An unwarmed mailbox in the pool will drag down your results.
Use similar accounts. Mailboxes on the same domain, with similar age and reputation, behave more consistently.
Keep per-account limits conservative. Rotation lets you scale by adding mailboxes, not by pushing each one harder.
Check account health regularly on the Email Accounts page and pull any mailbox whose health score drops out of the pool.
Monitoring
Per-account sending volume and health are shown on the Email Accounts page. Campaign-level results are in the campaign's Analytics tab.